Engineering

The engineering department of a hotel has great importance in as much as it provides utility services like electricity, steam, hot water, air-conditioning, and refrigeration, maintenancehotel maintenance hospitality study

 

engineering, and services of various other equipment.

 

This department in the hotel is very important and should be training be on the schedule for all the team continuously.

  • The Housekeeping Department will call the engineering desk with all room-related maintenance requests.
  • The Housekeeping control desk attendant also entered the maintenance tasks onto the Hotel Management System (PMS).
  • The engineer will respond to the work order or maintenance requests within 15 minutes and facilitate repairs.
  • The housekeeper will write a maintenance request to be handed into the office by the end of the working day.
  • The engineer who facilitated the work will set the maintenance request to be resolved.

Pollution Control in Hotel

Hotels are properties where very high intensity of human and machine activities occur day in and day out. This is bound to produce all sorts of pollution and is subject to very stringent pollution control measures.

The various sources of pollution are-

  1. Domestic, industrial, and hospitality industry effluent (liquid waste) to water bodies or sewage pollution.
  2. Domestic, industrial, and hospitality industry gas emission (furnace, ovens, engine) released to the atmosphere or gas pollution.
  3. Solid waste and sewage pollution to soil.
  4. Solid waste and sludge pollution to soil.
  5. Thermal pollution.
  6. Noise pollution.

Hotels produce a lot of wastewater and many of them have now installed their own sewage treatment plant (STP), which contributes greatly in reducing pollution as well gaining economy by way of reuse of clear water. This pollution can be minimized at the source itself by restricting chemicals that mix with water, restricting/eliminating garbage, and oil or unknown chemicals in the waste system (for example, detergent water in the sewage severely affects performance of the septic tank) etc. Hotels produce a lot of grease and fat in kitchen and detergent water in laundry, which go to the wastewater. The presence of detergent makes septic tank treatment less effective. However, hotels have grease traps in the wastewater lines.

Waste material may be broadly classified as a) liquid waste and ii) solid waste.

Liquid waste is commonly known as sewage. Although the bulk nature of sewage is liquid, it also contains some solids produced by human called sullage and would primarily consist of wash-basin water, faeces, urine, laundry waste, and other material that flow into the drainage system of the holding. Sewers are the conveying pipes for the wastewater and sewage is the total system of collection, transportation, and safe disposal of wastewater.

Hotel wastes and their sources

  • Garbage: It is the both solid organic and inorganic waste of varying nature produced from the different sections of a large hotel, like building (from dusting and sweeping), gardens (from wood and waste vegetation), kitchen (from cooked and uncooked food waste), dinning rooms (from left over cooked food waste).
  • Sullage: It comprises of wash water waste from bathrooms, building drains and kitchen.
  • Sewage: It is the discharge from the water closets
  • Exhaust gases: These are the gaseous discharge of stale and spent air from the general building; spent air, odour fumes and oil vapour discharge from the kitchen; poisonous gas and spent air from the generator room.
  • Chemical waste: coming from the water treatment plant.

Types of wastes

Garbage: This can be divided in the following components-

  • Solid organic waste material: Generally comprises of i) Plastic material scraps, ii) Wooden material scraps, iii) Paper, iv) Linen.
  • Solid inorganic materials: Normally comes from i) Dust from sweeping and dusting, ii) Metal scraps, iii) Glass scraps, iv) Chemicals.
  • Liquid organic waste material: Usually generates from i) Oils, ii) Soap solutions, iii) Sewage drain water.
  • Liquid inorganic waste: Generally comes from i) Sullage drain water, ii) Building wash drain water, iii) Rain water.
  • Gaseous organic and inorganic waste: Main sources are i) Water vapour or moisture, ii) Smoke, which is essentially suspension of carbon particulates in air, iii) Stale air exhaust from the buildings, iv) Fuel waste gases from a) kitchen and b) generator exhaust, v) Oil vapours from kitchen as result of cooking.

Established disposal methods

  1. Recycling: It is the process of material salvages, i.e. recovery and reprocessing of waste materials to manufacture new objects from the processed material. The materials reused in recycling serve as substitutes for the raw materials obtained from increasingly scarce natural resources such as petroleum, natural gas, coal, mineral ores and trees. Recycling can help in many ways like:
  • It reduces the quantity of solid waste to be deposited in the landfills; land filling has become increasingly difficult due to unavailability of vacant land.
  • Recycling reduces the pollution of air, water and land resulting from the waste disposal.
  • Recycling saves power, which is used to excavate and process the raw materials.

            Typical materials that can be recycled are-

  • Solid organic wastes- mainly comprises of paper, wood and plastics.
  • Liquid organic wastes- old lubricating oil from the engines and machines can be recycled to produce cheap quality lubricating oil for ordinary use.
  • Solid inorganic wastes- these are coming from all the metal scraps and all the broken scraps. After collection from the different sections of the hotel the solid wastes are dumped in different bins. The bin materials are then dispatched for the proper recycling process.
  1. Land filling: The waste materials which have no recycle value are used as filling materials to develop the low lying land areas into level lands. But prior permission has to be taken from local authorities. These can be used to establish new colonies, landscape parks and vegetable or agricultural parks around the city. The waste materials are dumped together with lime and insecticides and covered with a layer of the earth. As the layer decomposes and settles down, new layers are added till the level is a bit higher than the required level. The area is left over for a period to weather and get compacted and to settle down to a proper level.
  2. Disposal in sea: For the establishment near the sea shores where waste lowlands are scarce, the waste materials can be dumped, with permission of authorities, in the deep sea away from the shores. Proper care must be taken so that the dumped materials should not make any harm to the marine and biotic life near the shore, does not hamper the sea traffic and that the sea waves may not throw the waste back onto the shore.
  3. Incinerating: When the dumping facilities are not available or the waste may spread infection, the refuge is burnt in incinerators or large scale refuge burning furnace. The heat developed by burning is used to preheat new moist waste and also to heat water which can be reused for various odd jobs, washing and or heating of the building in winter.
  4. Irrigation: The sludge from the baths and the kitchen and building drains is used to irrigate the flora around the hotel site. Care is to be taken that the water is properly treated and disinfected before use.
  5. Cattle feed: If the hotel maintains its own cattle and poultry firms, the cooked and uncooked solid food waste may be used to feed the animals of the farms. The waste contains good food value and used to supplement the main diet of the animal. If the hotel has no such firms of their own the food waste may be sold to the local firms. With the permission of local authorities it may be dumped in low-lying areas to decompose and turn into manure for use in vegetable firms. The solid wastes from the kitchen, dinning rooms etc. is collected at a central isolated place and then machine-compacted into bundles which can be later dispatched for disposal at sites.

         7. Disposal in the atmosphere: The general waste gases are vented into the atmosphere. Care should be taken to dispose of the gases high up in the atmosphere through chimney, kept in the direction of wind flow. Instead of a single discharge, a scattered discharge system is used to better mix and dilute the waste gases in the atmosphere. Kitchen exhausts, comprising fuel waste gases and oil vapors need specialized disposal arrangements.

       8. Disposal of kitchen exhaust gases: The most common source of energy in the kitchen is hydrocarbon fuels. These fuels, on burning, produce wastes like-

                i) Ash: It is powdered inorganic waste material and causes land pollution.

              ii) Gases: It forms due to burning and cooking produce the following components:-

  • Carbon dioxide– The average normal level of CO2 in the air is 0.02%. Higher levels cause discomfort like headache, dizziness, sleep, nausea, etc. Gas is mainly responsible for global warming.
  • Carbon monoxide– This is produced due to improper and incomplete burning of the fuel. As a highly poisonous gas, it is responsible for the destruction of red blood cells of the blood and blood clotting and reduces the oxygen supply to the tissues, causing death.
  • Smoke– Burning of organic fuels is associated with the production of smoke, which contains micron-sized carbon ash particles’ suspension in waste gases. The micron-size suspended particulate matter leads to respiratory problems.
  • Cooking fumes– Oil, spices, and other ingredients are used to cook food. The cooking fumes are composed of water and oil vapors and spice smell-chemicals vapors.
  • Waste gases– These produce from fuel burning and cooking fumes and are responsible for

                                 i) Breathing and respiratory problems.

                                ii) Dirty building interiors and exteriors.

                                iii) Fire hazard- The thick oil-dart layer may catch fire due to high fuel gas temperature. This fire spreads easily and engulfs the combustible materials fixed on the walls.

                                iv) Food and spice smells cause breathing problems and eye irritation.

         9. Methods of controlling kitchen wastes:

  • Control of ash- The ash content in solid fuels is highest while that of gaseous fuels lowest, resulting in its calorific value highest, so the use of such fuels (LPG or city gas) is preferred. Electric heating is totally gas and smokeless, but the use is restrictive due to the high cost.
  • Control of fly ash- Fly ash traps must be used to trap the fly ash in the kitchen exhaust pipe. The traps should be cleaned at proper intervals. The collected ash may be used in landfills.
  • Control of carbon monoxide and dioxide gases- Properly designed burners that can have complete combustion should be used.
  • Control of oil vapors- The oil vapors of the kitchen fumes should be burnt in preheaters before they reach the ash traps. There are two types of preheaters, one is electrically heated and another one is gas heated.

       10. Disposal of sewage: If facilities are available, the sewage from the toilets is dumped in the local municipal sewer system. In case such a facility is not available the hotel authority will have to establish and maintain its own sewage treatment plant.

Sewage Treatment Plant

The sewage is treated properly and disinfected according to the local rules. The clean water from the treatment plant is used to irrigate lawns and flora of the hotel. The treated sewage slurry is dried in open land in the sun to turn into good quality manure cakes which may be either used in the hotel gardens or sold.

Water is treated in waste water treatment plants or effluent treatment plants. Such treatment plants treat water in three phases:-

  1. Primary treatment: This involves removal of large solids. It is mostly done by using screens and filters. These remove the large solids from the waste water.
  2. Secondary treatment: In the second step of treatment the biological degradation of organic wastes in waste water is done by micro-organisms.
  • Tertiary treatment: Here the removal of balance wastes is done which could not be removed by primary or secondary treatment. There are many methods available depending on the nature of the waste. Some methods which are commonly used are reverse osmosis, activated carbon etc.

Septic Tank– A sewage treatment process commonly used to treat domestic wastes is the septic tank. It may be a concrete, cinder block or metal tank where the solids settle and the floatable materials rise. The partly clarified liquid stream flows from a submerged outlet into subsurface rock-filled trenches through the wastewater can flow and percolate into the soil where it is oxidized aerobically. The floating matter and settled solids can be held from six months to several years, during which they are decomposed anaerobically.

Generator Exhaust

For big hotels it is essential to maintain their own emergency back up electric power arrangement. Diesel generator sets are used for this purpose. The exhaust from the gen sets is very irritating and contains carbon particulates, carbon monoxide and cancer producing gases. The sets also produce a lot of vibration and noise. To mitigate these conditions following methods are used:-

  1. The gen sets should be installed at proper rooms at a distance from the main hotel building to reduce vibration and noise.
  2. Vibration absorbing pads and noise suppressing arrangement are to be provided.
  3. The gen set room should be so oriented so that the exhaust is driven away from the main building with the natural airflow moist of the time of the year.
  4. The exhaust is disposed through high chimneys with traps for the solid particulates.
  5. Multi discharge system is used to dilute the waste gases.

Chemical Wastes

If the hotel is not getting the municipal water it has to manage its own water supply through deep tube-wells. The water from these wells may require chemical and disinfecting treatment to make it potable. The chemical waste from the treatment plants should be discharged for dilution in water mass or drying up in pits, according to the local health and safety regulations.

Air Pollution

Presence of harmful gases and solid particles in air leads to air pollution. It is increasing in big cities very rapidly and has an adverse effect not only on human beings but also on other animals and plants.

Causes of air pollution:

  1. By burning of fossil fuels in power houses, industries and vehicles. This gives off gases like carbon monoxide, sulphur dioxide and nitrogen dioxide.
  2. Sulphur dioxide is formed from burning of coal and car exhaust. When it combines with oxygen and water in the air it forms sulphuric acid. The mixture of acid and rainwater that falls on the earth is called acid rain.
  3. Increasing volume of carbon dioxide is a major cause of deforestation.

Effects of air pollution:

  1. It causes irritation of eyes, dizziness, headache and respiratory diseases like bronchitis and asthma.
  2. Automobile exhaust gases cause damage to liver and reproductive organs.
  3. Excess carbon dioxide gas in the atmosphere traps the heat of the sun leading to a rise in the temperature of the earth over a period of time. This is called Greenhouse effect. Also this effects global warming.
  4. Acid rain corrodes metals and damage marble. This also affected the marbles of Taj Mahal, responsible for the death of many aquatic animals, soil fertility by making the soil acidic etc.

Control of air pollution: Following measures can check the pollution to some extent-

  1. Changing the energy source from fossil fuel to renewable energy sources like solar, wind, bio gas.
  2. Use of pollution control equipments like fabric filters, wet scrubber and electrostatic precipitator etc. in related industries.
  3. Use of CNG as fuel for buses instead of diesel.
  4. Use of unleaded petrol.
  5. Use of car pool by office goers and school children.
  6. Industries to treat gases released from the chimney.
  7. Shifting of industrial units from residential areas to industrial areas which are far away from the cities.
  8. Creating awareness and education among the masses.
  9. Hotel industry must conduct research work and find better eco-friendly technology that reduces pollution.
  10. Follow the norms already set by the respective authorities.

Water Pollution

Water pollution refers to the presence of harmful material in water. Pollution makes water unsafe for drinking, washing, cooking and sometimes even for recreation. According to the World Health Organization (WHO), water related diseases could kill 135 million people by 2020.

Causes of water pollution:

  1. When untreated sewage (waste water from sinks, showers and toilets) is released into rivers, it is broken down by bacteria and oxygen is consumed in this process. This causes the deficiency of required level of oxygen in water and death of living organisms.
  2. Industries often release waste (contains certain metals) into rivers which are harmful for living organisms.
  3. Throwing of dead animals and dumping of other solid wastes into water.
  4. Bathing and washing of clothes by human beings in ponds and rivers.
  5. Excessive use of detergents.
  6. Excessive use of fertilizers and pesticides cause water pollution as they are carried to water sources with rainwater.

Effects of water pollution:

  1. Can cause water-borne diseases like typhoid, jaundice, dysentery, cholera etc.
  2. It destroys aquatic plants and animals.
  3. Because of the pollutants abnormal growth of certain plants may be there at the same time these may lead to death of flora and fauna.
  4. Many pollutants released from the industries have got adverse effect on human health. For example, mercury damages nervous system; cadmium makes bones fragile etc. Pesticides may cause cancer and affect our immune system.

Control of water pollution:

  1. Sewage water should be treated before being released.
  2. Chemical waste released by factories should be treated before being released into rivers.
  3. Dead bodies of animals should not be thrown into water bodies.
  4. Creating awareness amongst masses regarding importance of clean water.
  5. Usage of inorganic fertilizers and pesticides in agricultural fields should be reduced.
  6. Existing laws and regulations should be properly enforced.

Noise Pollution

The word noise derived from the Latin term nausea. It has been defined as unwanted sound, a potential hazard to health and communication, dumped into the environment, with regard to the adverse effect it may have on unwilling ears.

Understanding noise:

  1. In simple language, noise is the unwanted and or unpleasant sounds, which masks (covers) the intelligible sounds and makes hearing difficult.
  2. Noises are random (unpredictable and unsystematic) and undesirable sound signals, which produce an unpleasant hearing effect and at the same time mask the desired intelligible sound signals.
  3. In acoustics, noise means any undesired sound, which is an irritant and objectionable or, which interferes with other intelligible sounds that are being listened to.

Types of noise:

  1. In music, the effect of the complete range of audible sound wave frequencies heard simultaneously (at the same time), is analogous to white light, which contains all the frequencies of the light spectrum seen simultaneously. This is known as white noise. The sounds of cymbals and big drums have white noise characteristics. White noise is a periodic sound of non-uniform wave pattern of constituent frequencies and of random amplitude, occurring at random intervals.
  2. The detrimental effects of noise are increasing day by day due to the increase of industries, types and number of transport vehicles, advances in information and entertainment technologies etc. has added further to the natural noise sources.
  3. Due to the above reasons noise is present in every walk of our lives like, at home, workplace, during travel on roads and also during leisure activities.

Sources of noise:

      The sources of noise can be divided into two categories, like

  1. Natural– Any sound created by natural sources which disturb hearing. Example, sound of big streams, waterfalls, storm, animal noise etc.
  2. Artificial– Any noise created by manmade sources or machines such as :

External Sources:

  1. Transport– a) Roads: Due to different types of transport modes and transport generated noise. b) Air: Planes and helicopters. c) Water: Steamers and powerboats. d) Rail transport: Trains, subway trains and trams etc.
  2. Construction– a) Of big buildings b) Sport stadia.
  3. Industry– Depends on the type, location and process of the industry.

Internal Sources:

 Equipments and systems fixed in the building, like air conditioners and air conditioner plants, ventilation systems, exhaust fans, compressors, lifts and elevators, ice machines, laundry machines etc.

Modes of Entertainment:

Open areas- music groups, games, function areas, public gathering and revelry.

Covered areas- discos, theatres, feasts and public gathering.

Effects of noise on environment : Noise effects the bio world largely. It impedes the growth of the plant world, while it has got very adverse effect on animal world, specially on human, like-

Human health: 

  • Retards the process of growth, 
  • Induces high blood pressure (hyper tension), 
  • Effects the digestive process and promotes the chances of ulcers, 
  • Damage to hearing system. Noise at 60 db become unbearable, while noise at 120 db may cause permanent deafness, 
  • Nervous breakdown, 
  • Induces irritation and aggressiveness, 
  • Circulatory disturbances like palpitation, breathlessness and dizziness.

Privacy: Infringement of privacy

Disturbed environment: 

  • Communication,
  • Difficulty in concentration. 

Measure of Noise

A decibel is a standard for the measurement of noise. The zero on a decibel scale is at the threshold of hearing, the lowest sound pressure that can be heard, on the scale. According to Smith, 20 dB is a whisper, 40 dB is the noise in a quiet office, 50 dB is normal conversation, 80 dB is the level at which the sound becomes physically painful.

The loudness of noise is measured in logarithmic units known as decibels (dB) while the intensity is measured in watts per square meter (watts/m2). The unit of sound level intensity (Loudness) is a bell (ten decibels), named after Alexander Graham Bell. A list of common sound levels is given below:-

  1. Jet aircraft – 120 dB,
  2.  Heavy machinery – 90 dB,
  3. Busy street – 70 dB,
  4.  Conversation – 50 dB,
  5. Whisper – 20 dB.

Difference between the intensity of sound and loudness

While the intensity is the actual measure of force per unit area created by a sound signal, loudness is the level of sensation by a person. For example, a sound may be very loud for a small baby; it is normally loud for an adult while it may be very feeble for an old man with impaired hearing.

Sensitivity to sound

It depends on the factors like, 

  • Age, 
  • Sex, 
  • Present health condition, 
  • Present stress condition, 
  • Time of the day, 
  • Present activity, 
  • Acoustic factors.

Control of Noise Pollution:

  1. A green belt of vegetation (green muffler) could be used. The extra expanse of trees will absorb the noise.
  2. Zoning should be specified. In each zona, the limit to which noise can be caused is specified.
  3. Proper lubrication of machines and equipment will reduce friction and noise.
  4. Earplugs and earmuffs could be used in higher noise areas.
  5. Noise pollution can be curbed by creating awareness and education.
  6. Proper research work to be done to find better eco-friendly technology that reduces noise pollution.

 

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Water System

Among the most important distribution systems in the hospitality industry water is the most important amongst all and generally, water provides a public utility similar to electrical energy. Hospitality industries are totally dependent on the supply of potable water and sanitary drainage network system. The primary sources of freshwater are lakes, rivers, and groundwater. Due to pollution affects rivers and lakes are not considered as source and finally the only source remains as groundwater. Again due to the scarcity of groundwater, there is also a need for recycling and conservation.

Water is classified as hard and soft depending upon its behavior towards soap solution.

Soft water: Water that readily forms lather with soap is called soft water. Rainwater, pond water, distilled water, etc. are examples of soft water. Soft water is slightly acidic.

Hard water: Water that does not easily form lather with soap is called hard water. Seawater and groundwater from tube wells are sources of hard water. Hard water is alkaline in nature.

Advantages of soft water  

  1. Soft water consumes less soap for cleaning clothes.
  2. It is good for cooking, imparting good taste to cooked food.
  3. Soft water does not produce crust or deposit any scale in the pipe or other equipment that uses water.

Disadvantages of soft water

  1. Soft water is usually less palatable to drink due to a lack of minerals.
  2. Soft water does not provide vital minerals such as calcium and magnesium necessary for the body.

Advantages of hard water

  1. Hard water provides a good taste for drinking.
  2. It provides vital minerals necessary for the body.

Disadvantages of hard water

  1. The use of hard water causes wastage of soap and detergents. On average, hard water will destroy about 3 lb of soap per gallon of water. This also shortens the life of clothing and textile materials in the laundry.
  2. Scale is precipitated out of such water, which forms thick white crust (called scaling) inside pipes that carry them. This crust or scale a) gradually reduces the internal diameter and size of pipes, b) lowers the efficiency of the heating system by retarding the transmission of heat from the furnace or heating coil to the water inside the pipe, and c) interferes with the functioning of flow control valves in the pipeline.
  3. Hard water is not suitable for the paper, sugar, textile, and pharmaceutical industries
  4. Some people complain of dry skin after bathing in hard water.

Hardness of water

Total hardness is a test for overall water quality. There is no health concern associated with it. The degree of hardness is generally defined as calcium carbonate, equivalent of calcium and magnesium ions, present in water and is expressed in mg/L. In simple terms, hardness is a measure of how much calcium (and to a much lesser extent, magnesium) is in the water. Water hardness industry measures it in grains per litre, where 1 grain/litre = 64.72 mg/L.

pH value of water

The pH value of water is calculated as the logarithm of the reciprocal of hydrogen ion concentration (power of hydrogen and hence the term pH) present in water. It is, thus, an indicator of the acidity or the alkalinity of water. If pH of water is above 7, it will be alkaline and if it is less than 7, it will be acidic. The maximum acidity will be at zero value of pH and the maximum alkalinity will be at a value of pH equal to 14. Although pH value and hardness do not indicate the same property of water, the presence of carbonate ions in water (sometimes called ‘carbonate hardness’) pushes it towards alkalinity, and hence hard water is likely to have a high pH. A pH greater than 8.5 could indicate that the water is hard. Since measurement of pH is relatively simple, this could act as a reliable method to test the hardness of water.

The hardness of water is mainly due to the presence of dissolved bicarbonate (HCO3), chloride (Cl), and sulfate (SO42-), salts of calcium (Ca), magnesium (Mg), and iron (Fe). Sodium (Na) salts do not cause any hardness. All these salts that cause hardness to come from the rocks, get dissolved in the groundwater by way of rainwater percolating through the rock.

Ordinary soaps are mainly sodium and potassium salts of organic fatty acids such as stearic acid, palmitic acid, and oleic acid. When soap is added to hard water, calcium and magnesium salts dissolved in water react with the salts in the soap and form insoluble scum. The reaction occurs-

Na/K stearate/palmitate + Ca/Mg salt → Ca/Mg stearate/palmitate + Na salt

           (soap salt)          (hard water salt)             (insoluble scum)

No soap in the mixture (mixture of hard water and soap) will form lather till all the salts present in the hard water are removed as scum. Thus soap is consumed without producing lather needed for cleaning clothes, resulting in a great wastage of costly soap. Synthetic detergents can overcome this problem as they form soluble salts of Ca and Mg and do not form a scum or soap curd.

Types of hardness

Depending upon the nature of the dissolved salts, hardness maybe

  1. Temporary or carbonate hardness
  2. Permanent or noncarbonate hardness

Temporary hardness- It is caused by the presence of dissolved bi-carbonates of calcium    [Ca (HCO3)2].

Permanent hardness- It is caused by the presence of chloride and sulfate salts of calcium and magnesium like calcium chloride (CaCl2), calcium sulfate (CaSO4), magnesium chloride (MgCl2), and magnesium sulfate (MgSO4)

The reduction or removal of hardness from water is known as water softening. It is done mainly for the reduction in soap consumption, lowering the maintenance cost of plumbing fixtures, boiler tubes, and to improve the taste of food, etc., and saving energy.

The permissible hardness for public supplies normally ranges from 75 to 115 mg/L (14.25 mg/L is equivalent to one degree of hardness. Different methods for removal of hardness are shown below:-

The temporary hardness of water can be removed either by boiling or by adding lime to the water. The chemical reaction takes place (in boiling process) as

Ca(HCO3)2    +    Heat  →  CaCO3 ↓       + CO2 ↓      + H2O

(Calcium bicarbonate)                             (Calcium carbonate, insoluble)

Mg(HCO3)2    +    Heat  →  MgCO3 ↓       + CO2 ↓      + H2O

(Magnesium  bicarbonate, insoluble)

The chemical reaction takes place (in addition of lime or Clarke’s process) as

Ca(HCO3)2          +         Ca(OH)2          →        2CaCO3  ↓    +     2H2O

(Calcium bicarbonate)    (Hydrated lime)         (Calcium carbonate, insoluble)

Mg(HCO3)2          +         2Ca(OH)2          →      Mg(OH)2 ↓   +    2CaCO3  ↓    +     2H2O

There are six methods for removing permanent hardness like,

  1. Washing soda process
  2. Base exchange process (or Zeolite process)
  3. Lime soda process
  4. Caustic soda process
  5. Ion-exchange process or demineralization(DM) process
  6. Calgon process
  1. The chemical formula of washing soda is Na2CO3. The reaction takes place when washing soda is added to hard water is

         Na2CO3    +      CaSO4             →              CaCO3 ↓    +        Na2SO4

         Na2CO3    +      MgCl2              →              MgCO3 ↓    +        2NaCl

        2. Hardness can be very effectively and economically removed by using a chemical called zeolite. A zeolite softener resembles a sand filter. The hard water enters the softener from top react with the zeolite and the softened water is collected through the strainer at the base. The reaction takes place as

      Na2Z              +        Ca or Mg salt       →           Na2 salt     +     Ca or Mg zeolite

(Sodium zeolite/active zeolite)           (Hard water salt)      (Exchanged or used zeolite)

After a few days of operation, all the active sodium zeolite changes to used calcium and magnesium zeolite. These can be converted back to the active sodium zeolite by reacting it with a 10 percent solution of sodium chloride (common table salt solution). This process is known as regeneration. The reaction takes place as

CaZ / MgZ        +          2NaCl              →           Na2Z              +         CaCl2 / MgCl2

 (used zeolite)          (sodium chloride              (regenerated              (dissolved salt removed by

                                          Solution)                    zeolite)                     flushing water)

Advantages of zeolite process- 

  • Zero hardness can be obtained and have specific uses in textile industries, boilers, etc. 
  • The plants are compact, automatic, and easy to operate. 
  • The running, maintenance, and operation (RMO) cost is quite less. 
  • It also removes iron and manganese from water. 
  • There is no problem in treating water of varying quality.

3. In the lime soda process, in addition to washing soda lime is added to remove temporary hardness. Hydrated lime reacts with bicarbonates of Ca and Mg.

4. Caustic soda can be used to remove both carbonate (temporary) and non-carbonate (permanent) hardness. This process is very efficient for low alkalinity water. Calcium and magnesium hydrogen carbonates react with caustic soda to produce insoluble calcium carbonate and magnesium hydroxide. The reactions are-

            2NaOH         +        MgSO4           →         Mg (OH)2   ↓        +      Na2SO4       

            2NaOH         +         CaCl2            →          Ca (OH)2   ↓         +      2NaCl  

            4NaOH         +        Mg (HCO3)2   →         Mg (OH)2   ↓        +      2Na2CO3    + 2H2O      

            2NaOH         +        Ca (HCO3)2   →         CaCO3   ↓       +      2Na2CO3    +   H2

5. There are many types of equipment in the industry like water boiler, other process equipment, and scientific apparatus water boiler, and others to produce insoluble calcium carbonate and magnesium hydroxide which need water free of minerals. The process by which the minerals are removed is known as demineralization (DM) and the plant is known as the DM plant. It is very suitable for producing water of any desired hardness or even mineral-free water. The demineralized water is sometimes called deionized water and is as pure as distilled water.

The process consists of passing the water through cation exchange resins, which produce almost similar effects as are produced in the zeolite process, except that hydrogen (instead of sodium) is exchanged for the basic metallic ions. The cation exchange resins in fact are phenol aldehyde condensation products whose chemical formula is H2R (H represents hydrogen ion and R represents the organic part of the substance).  The reaction takes place as below:

Ca (HCO3)2         +         H2R              →            CaR           +       2H2O       +    2CO2   ↑

(fresh cation exchange resin)                 (exchanged or used resin)

Na2CO3           +         H2R              →              Na2R          +          H2O        +      CO2  

6. Calgon is the trade name of a complex salt, sodium hexametaphosphate (NaPO3)6. Calgon ionizes to give a complex anion, which subsequently combines with Ca and Mg ions in hard water.

(NaPO3)6   or   Na2 (Na4P6O18)         →         2Na+        +          Na4P6O182

                                                                                                  (complex anion)

In addition of Calgon to hard water causes the calcium and magnesium ions of hard water to displace sodium ions from the anion of Calgon according to the following reaction:

CaSO4        +       Na2 (Na4P6O18)      →        Na2SO4        +        Ca (Na4P6O18)

This results in the removal of calcium and magnesium ions from hard water in the form of a complex compound with Calgon and thus the water softened. Sodium salts are released into the water without causing any hardness. It is being dosed into the water used for washing machines, dyeing work, etc.       

Water distribution system

In cities and towns normally water is supplied by civic bodies through public water lines. It is required to have a storage reservoir on top of the building. The civic body charges the establishment for water consumption either lump-sum or through recording of consumption by water meters. However, many hotel units particularly in isolated areas find it economical and convenient to have their own bore well pumps within the premises that provide raw water which is further treated for consumption. But nowadays lifting of groundwater through the digging of wells needs permission from government departments. A hotel establishment needs a lot of water for various essential functions. An average figure will be 200 liters (about 50 gallons) per person per day.

Coldwater is used for diverse functions in a hotel like:-

  • Drinking
  • Cooking in the kitchen
  • Kitchen, restaurant, and lavatory wash sinks and washbasins
  • Lavatory flush
  • Laundry
  • Estate and floor cleaning purposes
  • Fire-sprinkler system
  • Cooling the diesel generating set, refrigeration plant, etc.
  • Hot water and boiler make up water
  • Gardening etc.
  • In swimming pool and other water bodies, if any.

In India central-room heating is not required and hotels normally do not use such systems. Hot water is used for laundry purposes and kitchen, throughout the year and for the personal use of the guests, particularly during the winter season in hotels in plains and throughout the year for hill-station hotels.

Water quality requirements are different for different uses in the hotel industry. For example, water lines for drinking, kitchen, and washbasins/sink must be supplied with bacteria-free soft water, while laundry and other functions can work with plain soft water. In modern establishments, a laundry line is connected with the drinking water line. Lavatory washbasin and water closets (WCS) may be provided with only soft water. In many modern units, wastewater is collected, treated, and recycled. Rain-water harvesting has assumed great importance and in many establishments, this may supplement the main water supply system.

There are several water distribution systems used in hospitality and catering industries, like

  1. Upfeed system
  2. Upfeed system with circulating pumps
  3. Downfeed system (cold water only)
  4. Downfeed circulating system
  5. Combination system
  • It is the most commonly used water distribution system where the pressure of water is sufficient to force water throughout a hotel building of six floors or less in height. The maximum number of floors that can be fed with this system depends on pressure, the resistance of pipe, and the height of the building.
  • This system is used when the water pressure is inadequate and a circulating pump along with a return pipe is installed to increase water pressure and water to flow constantly throughout the system. This is frequently used on hot water lines to provide an adequate supply of hot water by making a provision of the water heater.
  • Here water is forced or pumped to a storage tank (overhead) located on the top floor of the building. When water is required, it flows by gravity from the storage tank to the tap. This system is used in very tall buildings.
  • It is very similar to the circulating puffed system. This technique is frequently used with hot water to ensure an adequate amount of hot water at each fixture.
  • It is a combination of speed and down feed systems. The feed system is used for the lower building levels and the downfeed system for the upper building levels. This system is probably the most efficient distribution system for multiple-floor hotel buildings because main water supply pressure is utilized to the full extent and additional pressure is generated by pumps to reach water on the water storage tank located on the top floor of the building.

The normal hot-water temperature requirements in the hospitality industry are:-

  • 110 degrees Fahrenheit or 43.3 degrees Celsius for domestic use.
  • Normal personal washing: 140 degrees Fahrenheit or 60.0 degrees Celsius.
  • Food production sinks 160 degrees Fahrenheit or 71.1degree Celsius.
  • Dishwashing: 180 degrees Fahrenheit or 82.2 degrees Celsius.
  • Pools and spas: 80-100 degrees Fahrenheit or 26.7 – 37.8 degrees Celsius.
  • It is highly recommended to label fixtures supplied with water above 120 degrees Fahrenheit or 48.9 degrees Celsius with a warning that the water is hot and dangerous.

Swimming Pool Maintenance

Swimming pool design, construction and maintenance are controlled by local development authorities in coordination with public health department. The equipment and their utility connections are frequently tested by these departments.

The fundamental pool device is the filter. The filter removes impurities from water and keeps clear and sparkling. The true test of adequate filtering is to toss a small coin into the pool at its average depth and to be able to distinguish one side of the coin from the one it rests on at the bottom of the pool. The filter must cycle pool water every six to eight hours. Water turnover cycle consists of forcing all the pool water through the filter in a specified time period. In a normal operation, one water cycle is required each day. If swimming activity increases, more than one water turnover cycle may be required. Normally, pool water is used for cleaning the filter and filters are cleaned by back washing. The instructions given by the manufacturer of the filter should be followed, as there is no set schedule of cleaning of filters. 

Swimming pool should be cleaned from time to time from debris, leaves, insects and soil by using various types of nets. The pH level of pool water should be between 7.2 and 7.6 or slightly alkaline. If pH exceeds 7.6 then there is a chance of developing water algae which may cause skin and mucous-membrane irritations to swimmers. If pH level falls below 6.8 metal equipment may corrode. Shock treatments are used to kill algae. Shock treatment means increasing the level of disinfectant from 1 part per

million of bromine to 5 parts per million (in case of chlorine it is 2 parts per million to 10 parts per million). In case of excessive growth of algae the pool must be cleaned after draining the water with acid chemicals known as acid washing.

Fittings in water distribution line

There are some important water line fittings such as valves, taps, cocks, tee, socket, nipple, bend and flushing cistern which are always present in any water-distribution line of a hotel. Valves and cocks are kept to a minimum in hot water line.

Valves, taps and cocks are fittings in water lines to regulate flow through the lines and are integral parts of any water-distribution system. The function of a valve is the same as a tap, i.e. to open and close or control flow of water through a line. The word tap is used when the valve is small in size and fitted just before any service utility such as basin, sink, shower etc. The flow of water in large pipelines is controlled by valves.

A tap is what we see at the draw-off end of water service line. They are normally screw-down type valves. Depending upon the directions of water entering the tap and coming out of tap they may be categorized as Bib tap, Pillar tap, Globe tap etc. Bib tap has a horizontal inlet and free outlet in the form of a bent tube called bib which prevents dust from entering into the free end and contaminating water when it comes out. Pillar tap has a vertical inlet and horizontal outlet through a bib. These are used in lavatory basins and baths. Globe tap has a horizontal inlet and vertical outlet, were used in baths and now replaced by pillar taps.

Cocks are normally plug-type valves and are quickly closed by a quarter turn of the knob as in a gas cock. This is used in a cold water system at the entry point of the civic water line into the premises and is called stopcock.

The term ‘valve’ is normally used to indicate controlling and most often for stopping or fully opening supply to a line and fitting. While stopcocks are plug type, valves may be screw-down type or sliding-plate type (like gate valve).

There are pipe fittings to facilitate layout of pipelines for branching (tee), joining of two pipes (sockets, nipples) and change of direction of pipelines (bends).

Flushing cisterns are normally of two types – Plunger and siphon type, Bell type. Both are supplied with cold water through ball tap and fitted with an overflow discharge outlet.

 

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Maintenance

Planned Maintenance– Equipment will be maintained throughout its working life, before a complete breakdown requiring replacement / major repair.

Preventive maintenance– Actions carried out on a time-based and condition-based schedule which detect, preclude or mitigate degradation of a component through controlling degradation to an acceptable level.    

Preventive maintenance is based on the principle “Prevention is better than cure”. It cannot prevent failure but can extend the working life of the machines.

Constant inspection and checking can predict failures and can avoid complete stoppage of service by keeping alternative facilities.

Philosophy of time-based preventive maintenance:-

  • Scheduling maintenance activities at predetermined time intervals.
  • Repairing or replacing damaged part before problems occur.

These are achieved through  i) Routine maintenance and ii) Scheduled maintenance programmes.

Routine maintenance– Cleaning of machines, regular lubrication of moving parts (bearings, door hinges etc.).

Scheduled maintenance– Done using experience and following manufacturer’s maintenance schedule. Schedule of machines are prepared, log books are maintained. Advantages are significant for equipment which does not run continuously but needs people having good knowledge, skills and time to perform this maintenance.

Philosophy of condition-based preventive maintenance:- (also called predictive maintenance)

  • Scheduling maintenance activities when mechanical or operational conditions demand.
  • Repairing or replacing damaged equipment before problem occurs.

Scheduling maintenance by periodically monitoring the machinery for excessive vibration, temperature, lubrication degradation, any other unhealthy trend that occurs over period of time.

When condition deteriorates to predetermined unacceptable level the equipment is shut down to repair or damaged components replaced to avoid occurrence of costly failure.

Basic Preventive Maintenance program consists of:-

  1. Regular periodic inspection of machines, utilities, buildings. The schedule is determined based on the experience of the maintenance engineer and the recommendations of the manufacturer.
  2. Preparing an information database regarding the nature and possible causes of the breakdown of different equipment to analyze and maintenance action can be taken to avoid repetitive occurrence.

Corrective maintenance- Sometimes it is called running maintenance. This takes place where minor repair work is carried out on machines initiated by formal work order from the machine user department. A work order can clearly or roughly identify the problem. The maintenance crew inspects the machine and does repair work in a short time. Corrective maintenance attempts to meet the known needs in an orderly and timely manner as per the requirement of the property.

Reactive maintenance- It is a maintenance action as a reaction to the failure of equipment or building civil work.

Breakdown maintenance is a strategy, emergency breakdown is related to emergency situations where failure occurs in spite of other modes of maintenance being carried out.

Philosophy of breakdown maintenance:

  • Allowing the machinery to the run up to the point of failure.
  • Repairing or replacing damaged equipment when problems occur.

Breakdown maintenance implies the restoration of a facility to almost its original condition for which it is designed either by major repair or by total replacement.

Modern equipment like modern cars, washing machines, vacuum cleaners, dishwashers, mincers, mixers, etc. is made with a high degree of sophistication and reliability. It is advantageous from a cost point of view to run them till they fail. Also true for electronic control systems like sensors etc. Electric bulbs may be replaced by a group replacement policy.

In breakdown maintenance there cannot be any delay in repairing or replacing the components, otherwise, the entire operation will come to a halt.

Advantages of Breakdown maintenance :

It saves a lot of regular maintenance work in terms of labour and spares inventory. If immediate restoration is required, there might be cost of overtime, emergency spares of high value. So it works well if equipment shutdowns do not affect service and if labour and material cost do not matter in case of emergency repair.

Emergency Maintenance is carried out when a portion of equipment suddenly fails  can be delayed keeping the post out of service  though it may cause a high level of inconvenience. For example, emergency repair of a guest room. It is an expensive way of maintenance.

 Disadvantages of Preventive maintenance:

  • It cannot eliminate complete failure.
  • It is more labour and time intensive.
  • Maintenance activities that are really not required are carried out.
  • It requires extra facilities and may lead to underutilization of facilities.
  • It is not economical for small property which has got cheaper and non-critical equipment.
  • Saving potential is not readily seen by management which usually focuses on running costs.

 Advantages of Running maintenance:

  • Has a lower cost due to no regular application.
  • Requires fewer staff for applying the scheme.

Disadvantages of Running maintenance:

  • Increased costs due to unplanned downtime of equipment.
  • May involve prolonged downtime if proper manpower and components are not readily available.
  • Increases labour costs, especially if overtime is needed.
  • May increase costs associated with repair or replacement of equipment on an urgent basis.
  • May result in possible damage to associated equipments.

Additionally two more maintenance practices are there for hospitality industry – Routine maintenance and Guest room maintenance.

Routine maintenance– General upkeep of the property is done on regular basis (daily or weekly). For example, cleaning of floor, sweeping the carpets, cleaning guest rooms etc.  They do not require any formal work order or skilled person.

Guest room maintenance– It has a special meaning in hotel industry. Some include it in the category of preventive maintenance, other call it corrective or running maintenance. The most important aspect of hotel industry is the level of comfort and ambience provided to the guest. When the guest steps in, the condition of the room is the assessing factor for quality. So this maintenance should have top-notch level of maintenance programme in hotel industry.

Example,  

i) Condition and proper operation of furniture, fixtures, equipment (TV, A/C etc.)  

ii) Appearance of walls, ceilings, condition of carpets, supply of water in the toilet, overall  cleanliness etc.                                                                     

Advantages of Preventive maintenance:

  • It is cost-effective in many capital intensive equipment.
  • Increases operational life of equipment.
  • Operates at design conditions. (lubrication, filter change etc.)
  • Gives maximum return on capital investment.
  • Reduces the number of equipment and service failures in a place.
  • Provides flexibility for adjustment in maintenance schedule.
  • Improve worker morale by reducing idle time.
  • Results in an estimated 12 – 18% cost saving over reactive maintenance programme.
  • Provides safety to personnel and property from hazards by reducing possible sudden breakdown ( for example, in boilers, compressors, transformers etc.)
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Fuels

FUELS: A substance which readily combines with oxygen to burn and gives off heat energy, can be used to heat a room, for cooking food, making steam in a boiler etc can be called a fuel.

Combustion: It is a phenomenon where elements (like carbon, hydrogen) or compounds or mixture of compounds/elements (like kerosene, petrol, diesel, LPG, coal gas etc.) combines with oxygen and reacts vigorously producing heat and light. Combustion is often accompanied by a flame.

Flame: Flame is the region in which chemical interactions among gases occur accompanied by evolution of heat and light. The flame occupies only a small portion of the combustible mixture at any time. Flame speed and thickness is largely affected by temperature, pressure and the type of fuel used. A flame has two zones, namely

  1. Pre-heat zone, where little heat is released.
  2. Reaction zone, where the bulk of chemical energy is released.

The calorific value of fuel: It is the heat released by a fuel during its combustion. For solid fuel, it is expressed in terms of Joule per Kilogram (J/Kg) or Kilocalorie per kilogram (Kcal/Kg). For a liquid fuel, it is expressed in Joule/liter or Kcal/liter, while for a gaseous fuel; it is in Joule/cubic meter or Kcal/cubic meter. There are two measurements of calorific value. One called net calorific value (NCV), is the useful heat we finally get by burning the fuel. The other is called gross calorific value (GCV), which is the NCV plus the heat that we could get back by condensing the steam as it comes out with the gaseous product of combustion. So, GCV is always higher than NCV. NCV is the parameter for comparing the heating values of different fuels.

Flashpoint: Flashpoint is the lowest temperature at which a liquid will give off sufficient vapor in air so that it ignites momentarily (without sustained burning) in presence of an external igniter like a flame or a spark.

Pour point: It is the lowest temperature of a liquid at which it will pour or flow when cooled under prescribed conditions. It is an indication of the lowest temperature at which the fuel oil is still readily capable of being pumped without getting excessively thick when cooled.

Specific heat: It is the heat required to raise the temperature of 1 Kg of substance through 1oC (in SI system). For fuels, it is usually expressed as Kcal/KgoC. This quantity is more important for liquid fuel as it is relatively high for them and the heat needed to heat it from room temperature to a desired high temperature for it to effectively burn. Light oils have low specific heat, while heavier oils have higher specific heat. These values usually vary from 0.22 to 0.28 for fuel oils.

Types of Fuels: Broadly there are three types of fuels, solid, liquid, and gaseous.

Solid fuel– Commonly used solid fuels are firewood, coal, and coke. Agro-residues like rice husk, bagasse, etc are also used as solid fuels. In missiles, rockets, etc. solid magnesium is used as a fuel.

In our country, solid fuels used in industries are mostly coal and coke. Coal can be classified as Bituminous, Anthracite and Lignite.

Anthracite is the geologically oldest grade of coal. It is a hard type consisting mainly of carbon with little volatile content and no moisture.

Lignite is the youngest from a geological perspective. It is a soft type consisting mainly of volatile matter and moisture with low fixed carbon.

Bituminous and semi-bituminous are common coal used in Indian industries. Bituminous and lignite produce a high quantity of smoke. Anthracite has less volatile matter and is smokeless. It is expensive but got a higher calorific value.

Another solid fuel is coke used in industries as fuel. Coke is produced by heating coal in a closed oven until its volatile content is driven off. Coke has a higher heating value and discharges little smoke. The calorific value is about 16,000 BTU/lb or 10,000 Kcal/Kg. 

Liquid Fuel– In industries liquid fuels used are Kerosene, Light Diesel Oil (LDO), High Speed Diesel (HSD), Petrol, Furnace Oil.

Gaseous Fuel– Commonly used gaseous fuels in India are LPG (Liquefied Petroleum Gas), Natural Gas, Producer Gas or Coal Gas. The calorific values of gaseous fuel is expressed Kcal per normal cubic meter (Kcal/Nm3), i.e., the volume corresponds to normal temp (200C) and normal atmospheric pressure (760 mm of Mercury)

LPG– It is a mixture of propane (C3H8) and butane (C4H10) plus small percentage of other hydrocarbons. It is a bye product of a petroleum refinery. It is a gas under normal temperature and pressure, but can be liquefied by moderate pressure and is stored, transported as liquids for ease of handling – takes 250 times less space than that taken by same mass in gaseous state. When the stored liquid comes out through the cylinders, comes under the reduced pressure in normal atmosphere, again evaporates to become gas to burn in ovens. To trace out leakage detection LPG is mixed with organic sulphide (Beta-mercaptan- C2H5SH). There should be adequate ground level ventilation where LPG is stored.

Natural Gas– Earth is the main source of natural gas. During exploration for petrol reserves, this is discovered. It is a very good fuel. Methane (CH4) is the main constituent (95% by volume). Other components are ethane (C2H6), butane (C4H10), propane (C3H8), pentane (C5H12), nitrogen (N2) and carbon di-oxide (CO2). Calorific value of natural gas ranges from 12,000 Kcal/m3 to 14,000 Kcal/m3.

Coal Gas or Town Gas- This is obtained as a bye product during the production of coke from coal in coke-oven plants. Coke is used for making iron from iron ore. Coal gas is a mixture of hydrogen, carbon monoxide, methane together with nitrogen, oxygen and carbon di-oxide and some other hydrocarbons, hydrogen sulphide and cyanide. This gas is toxic due to carbon monoxide. Due to hydrogen sulphide (smells like rotten egg) the leakage can be identified. Calorific value is about 4900 Kcal/m3.

Comparative fuel cost

Fuel cost can be calculated by using a formulae by arriving at the cost of a useful “therm”.

1 Therm = 100,000 BTU

Coke:- If coke cost  Rs. 12000 per ton or Rs. 4/- per lb then

1 therm cost = Cost per lb x 100000 / 12000  =  (4 x 100000 / 12000)  =  Rs. 33.33

A useful therm is the amount of heat output put to good use. Generally coke is considered as 60% efficient fuel. So, one useful therm costs =  Cost per therm x 100 / 60 = Rs. 33.33×100/60 =

Rs. 55.55

Gas:- To change cu.ft to therm, the heating power or calorific value of the gas to be known. This is generally shown on the gas cylinders.

Cost of Therm = Calorific value x Hundred of cu. ft / 1000 = A

Generally gas is calculated on 80% efficient.

So, one useful therm cost = Cost per therm x 100/80 = A x 100/80

Electricity:

1 unit of electricity produces 3412 BTU. Electricity is calculated as 100% efficient.

So, 1 therm costs = Cost per unit (B) x 100000 / 3412  = B x 100000/3412

Oil:-  1 gallon produces  165000 BTU. Oil is calculated as 75 % efficient.

So, 1 therm costs = Cost per gallon x 100000 / 165000 = C

So, one useful therm costs = Cost per therm x 100/75 = C x 100 / 75

Gas:  Stoves and burners are the appliances that are two of the arterial equipment in the kitchen of a hotel or a catering establishment. The correct choice of the type of ovens and burners are critical for energy efficiency, safety and functional performance of a kitchen. Burners are also used in boilers and many other equipments of hotel industry.

Oil stoves are not used for cooking in hotel industry. Oil burners are used in oil-fired furnaces of boiler and water heaters in a hotel. Purpose of oil burner is to make fine particles of fuel-oil, burnt at the mouth of the burner. This is known as the atomization which is different from vaporization. In atomization liquid remains liquid in tiny droplets form, but in vaporization liquid changed to gaseous state.

Out of above types of burners we will concentrate only on the twin-fluid atomizer type burners.

  1. Low air pressure burner- Air is provided by a blower, air acts as an atomizing agent. Oil is injected through a nozzle at the open end of burner where it gets atomized. Flow of air and oil regulated by valves. When oil flow rate is low, efficiency becomes lower. Air pressure in these types is 8 lb/ sq. in (about 330 mm of mercury- half the normal atmospheric pressure)
  2. Medium and High pressure burner:- Air is provided by a compressor. When load changes, the quantity of atomizing air does not change, only secondary air entering the system changes. So at lower loads also these burners are efficient.

Medium pressure burners have air pressure – 12 lb/sq in (80% of the atmospheric pressure).

High pressure burners have air pressure – 15 lb/sq.in ( 1 atmospheric pressure).    

Some chefs prefer gas cook tops since those can control heat more finely and more quickly. But some chefs prefer electric ovens as those can heat food more uniformly.

Low pressure burners use gas at low pressure (less than 0.15 Kgf/cm2 or 2 lb/sq. in or psi – about 1/7 th of 1 atm pressure). They are usually multijet type, gas is supplied from manifold / cylinder to a number of small single jets or circular rows of small jets around the inner circumference of circular opening in a block of heat resisting materials.

In high pressure burners, the gas jet draws air into mixing chamber and delivers proportional mixture to the burner. When the regulating valve opened, gas flows through a small nozzle into a venturi tube (a tube with a constriction at some section). At the narrow section, gas velocity becomes high when pressure drops – sucks air from outside through openings at the narrow section. This gas-air mixture flows through pipe to the burner.  

Different types of gas burners – There are five types gas burners like

  1. Giant: For rapid heating, for large utensils. Heat rate- not less than 12000 BTU/hr.
  2. Regular/Standard: For general cooking in average size pans. Heat rate- not less than 9000 BTU/hr.
  3. Simmering: For domestic in medium size pans. Heat rate- not less than 1200 BTU/hr.
  4. Pilot: For small families with small size pans. Heat rate- not more than 300 BTU/hr.
  5. Mini Pilot: For very small use with very small size pans. Heat rate- not more than 125 BTU/hr.

Now-a-days big size ranges available with heat output as 40,20,000 BTU/hr., some heavy duty fryers have 1,20,000 BTU/hr.

Safety Precautions (while using Gas Equipment)

  1. Equipments should be cleaned regularly, since gas contains sulphur, which corrodes metals.
  2. Gas cylinders should be placed in upright vertical position and never in horizontal position.
  3. Gas cylinders should not be tilted to an inclined position while being used, in order to completely utilize the gas.
  4. Cylinders must not be hammered.
  5. Cylinders and ovens to be placed in well-ventilated place.
  6. Inflammable materials should not be kept very near to gas bank.
  7. Empty gas cylinders to be immediately removed and kept at a place away from fire or other source of heat.
  8. Hose connecting the gas valve and oven should be checked at regular intervals.
  9. When work is over, regulating valve and burner switch should be in ‘OFF’ position.
  10. Everyday burner heads should be removed from ovens and pots to be cleaned with steel wire brushes.
  11. Open doors and windows before lighting burners.
  12. To put off oven, first regulating valve of the gas line is to be closed and then gas burner knob to be kept in ‘OFF’ position.

 Steps for efficient operation of LPG / other stove and burners

  1. Correct size of burner / nozzle should be ensured.
  2. If there is no pilot flame, ignition torch to be used.
  3. Attention should be given to fading or pulsation of flame.
  4. Flame size to be adjusted as per requirement.
  5. Proper shut down procedure to be followed
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Electricity

Hospitality and service industries require and use vast amounts of electrical energy. Electrical energy is a secondary energy source which means that we get it from the conversion of other sources of energy like coal, oil, natural gas, nuclear power and other natural sources, which are called primary sources. The energy sources we use to make electricity can be renewable or non-renewable, but electricity itself is neither renewable nor non-renewable.

We can formally define current as the free flow of electrons (negative charge) in any conductor.

Potential may be defined as the status of some entity (e.g. liquid in a tank, a metal plate at a given temperature, a terminal of an electric cell etc.) in respect of its ability to do some work. A body at a higher potential is said to have higher energy level than a body at lower energy level and if both are connected at identical situation, the energy will flow from higher energy level to lower energy level or there will be exchange of energy and potentials will become equal causing no further energy transfer, unless energy is added to maintain the potential difference. Let us have an idea of the following potentials.

Gravitational potential- A body at a higher height from the surface of the earth is at a higher potential than a body at a lower height.

Electric potential- It is the electrical potential energy per unit of charge that is associated with a static (not changing with time) electric field. It is measured in volts. The difference in electrical potential between points is known as voltage. Electric potential may be considered as ‘electric pressure’. Where this ‘pressure’ is uniform no current flows and nothing happens. Difference of electric potential causes flow of electrons in a circuit.

Temperature potential- A body at a higher temperature is at a higher thermal potential than a body at a lower temperature.

Concentration potential- A space having a higher concentration of some species (say, carbon dioxide) is at a higher carbon dioxide potential than a space having lower concentration.

Terminology

Current– It is the free flow of electrons in any conductor. Represented by I. ST unit is Ampere. Ex. 5 ampere or 5A.

Volt– Volt is force or pressure (potential difference) which causes the flow of electrons in any closed circuit. It is represented by V. Unit is volt. In practice there are two volts are in use, 220V for domestic purposes and 415V for industrial purposes.

Resistance– Electrical appliances when connected to a circuit it is a load or resistance through which current is to flow consuming electric power. Resistance may be defined as the property of a substance that opposes the flow of electricity through it. It is represented by R. Unit is Ohm (Ω).  

Ohm’s Law– The voltage drop across the load resistance of the circuit is directly proportional to the current flowing through it, provided physical parameters like length, cross-section, temperature, and material of the load resistance remain the same.

The mathematical expression is V α I.  So, V = R x I, where R is the constant of proportionality known as resistance responsible for energy waste.

One Volt– It is defined as the potential difference necessary between the ends of a conductor whose resistance is 1 ohm (Ω), to produce a current of 1 ampere (A).

Ampere– It measures the rate of flow of a current. One ampere = 1 Coulomb/sec

                                                                                                     = 1 / (1.6 x 10-9) electrons/sec

                                                                                                     = 6.25 x 108 electrons/sec

Watt– It measure power, that is, amount of electricity used by an appliance. 1000 watt = 1 Kw. Kw-hour is the unit of amount of current consumed.

Ex. 1000 watt appliance in use for 1 hour will consume 1 Kw-hour or Kwh, which is the measure of one unit of electric power or 2 nos. of 500 watt appliance in use for 1 hour, or 2 nos. of 250 watt appliance in use for two hours.

One unit (1 Kwh) produces 3412 BTU of heat.

We know, V = R x I,

So, V / R = I, if the voltage of the main supply =240 v., wire and other connections leading to a socket outlet has a resistance of 48 Ω, the socket-outlet is able to supply 5 amps.

Watts = Amp x Volt. Ex, A 5 amp socket using a current of 220 volts can supply an electrical appliance rated at 1100 watts.

Amp =Watt / Volt.  Ex, 4 nos. of 100 watt lamps using 220 volts could be safely supplied by a 2 amp plug.

 Closed Circuit: An electric circuit that provides an endless continuous path for uninterrupted supply of electric current.

Open Circuit: An incomplete electric circuit in which the normal path of current is interrupted.

Short Circuit: It is a closed circuit in which a direct connection is made with no appreciable resistance between the terminals of the source of EMF (Electromotive Force).

Series and Parallel Circuits: A Series Circuit is one in which the devices or elements of the circuit are arranged in such a way that the entire current passes through each element without division or branching into parallel circuits. When two or more resistances are in series in a circuit, the total resistance may be calculated by adding the values of such resistances, like R= r1+r2+r3……

A Parallel Circuit has more than one path for current flow. The same voltage is applied across each branch. If the load resistance is the same in each branch, the current flow in each branch will be the same. But if the load resistance is different in each branch, the current flow in each branch will be different. If one branch is broken, the current flow will continue through other branches, like

 Rtotal = 1 / (1/R1 + 1/R2 + 1/R3…….)

A Series Parallel Circuit has some components in series and some in parallel. The power source and control or protection devices are usually in series, the loads are usually in parallel. The same current flows in the series portion, but different current flows in parallel portion. If the series portion is broken, current stops flowing in the entire circuit. If a parallel portion is broken, current continues flowing in the series and the remaining branches.  

There are two systems of electric generation and supply like Direct Current (DC) and Alternating Current (AC).

DC is the kind of electric current that may or may not change the magnitude but the direction of the current (the sign of polarity of the voltage source terminals) will never change.

AC is the kind of electric current which change not only its magnitude but also its sign as time passes, in a definite manner.

 Conductor- It is a substance through which electricity flows freely without much resistance. Ex, copper, aluminium, water or wiring system of a building.

Silver is the best as conductor among all metals, but not used due to cost and deterioration due to atmospheric oxidation. Copper is the best as conductor, though costly but having better current carrying capacity and flexibility. Brass is used as contact elements in fittings and appliances.

      Material                        Resistivity (-m) at 20oC             (in descending order of conductivity)

       Silver                             0.165 x 10-7

       Copper                           0.17 x 10-7

       Aluminium                     0.266 x 10-7

       Brass                               0.5 to 0.9 x 10-7

       Iron                                 0.91 x 10-7

       Tin                                   1.15 x 10-7

Insulator- These are substances which offer maximum resistance so that they allow practically no electricity to flow through them. Example, rubber, asbestos, bakelite, mica, ebonite etc. Ceramics are used in utility poles.

                                                           

   Material                        Resistivity at 0oC    (ohm-m)

   Bakelite                                     1

   Distilled Water                         105

   Glass                               5 x 109  to  1013

   Mica                                1011    to    1015

   Porcelain                         1012    to     1013

 

Wires- These are used for carrying current from one point to another. Cable and wire are same, but cable is used for all heavy section insulated conductors, a wire means a thin section insulated / bare conductor. Wires are expressed in number of strands twisted together. Example, 3/22, 3/20 etc. A 3/22 wire means a cable has three smaller wires of 22 standard wire guage (SWG) stranded together.

Types of Conductors / Cables

Vulcanized Indian Rubber (VIR)- Copper wire covered with a rubber insulation with a protective cotton braid over it. It is now obsolete, used in irons where maximum flexibility is required.

Lead Alloy Sheathed Wires- VIR is unsuitable in damp conditions – a thin lead covering is made on VIR to make this type. These are expensive.

Cab Type Sheathed / Tough Rubber Sheathed (CTS / TRS) – These are moisture proof. These are cheaper than lead sheathed cables. These are also obsolete now.

Poly Vinyl Chloride (PVC) – Bare conductors are insulated with PVC insulation. These are used in domestic wiring system.

Flexible cable- These are made with two or three PVC wires in stranded position. These are used for temporary lines.

FUSE

Fuses are special devices that are inserted in the circuit and consist of wires of low melting point. A fuse is a device that cuts off the circuits when more than the predetermined value of current flows in a circuit. It is the weakest point of the circuit, which breaks when more than normal current flows in the circuit. 

Standard sizes of fuses are given below:-

  1. 2 amps (for lamp) – consuming not more than 480 watts at 240 volt
  2. 5 amps – consuming not more than 1200 watt at 240 volt
  3. 10 amps – consuming not more than 2400 watt at 240 volt
  4. 13 amps – consuming not more than 3120 watts at 240 volt

The material of the fuse is generally Copper-tin or Lead-tin alloy. In Lead-tin alloy there is 37% lead and 67% tin. The minimum length of a fuse is generally 65 mm to 100 mm.

Types of fuse holders are:-

  1. Semi-enclosed or re-wire able ( or Kit Kat)
  2. Totally enclosed or Cartridge type
  3. High Rupturing Capacity fuse (HRC)
  4. Miniature Circuit Breaker (MCB)

 WIRING

Type of wiring:    

  1. Cleat- Porcelain or wooden cleats are fixed on walls at a distance of 4 to 5 m apart. VIR or PVC wires are normally used in this type of wiring. Suitable for temporary wiring purposes (marriage halls, indoor fairs etc.), dismantled very quickly and materials can be reused.
  2. Wooden Batten- Wires are carried on wooden battens with clips. TRS or PVC wires are used. Installation is easy and less costly.
  3. Casing and Capping- Common type in indoor and domestic installations. VIR wires are used in PVC casing and finally covered by PVC capping. Wires are not visible from outside. This is costlier but more reliable and nice looking.
  4. Lead Sheathed- Lead sheathed wires are fixed by metal clips on wooden batten. The lead covering protects the wire from mechanical damage. As these wires are costly, these are not in use nowadays.
  5. Conduit- For workshops and public buildings these are best and desirable. VIR or PVC wires are carried through steel or iron pipes. Maybe over the walls or concealed.

Precautions to be taken in working or handling electrical equipment

  1. To be careful and not to be unmindful while working with electrical equipment.
  2. Immediately after the repair one should not energize the conductor without ensuring the safety clearance.
  3. The plug should not be disconnected by pulling cable.
  4. Before doing any work, the main switch should be kept ‘off’.
  5. Safety demands good earthing. So, earth connection should be good.
  6. While moving electrical appliances like table fan, iron, heaters etc. these are to be disconnected from supply, simply switching off is not enough- there might be leakage.
  7. Live wire should always be connected through switch.
  8. In case of electrical fire, water should not be used. Only CO2 extinguishers are to be used.
  9. Tools should not be used without handle. Pliers should not be used as hammer. Tester as screw driver.
  10. Any work to be done above ground, proper precaution must be taken while using ladders and to be done by qualified electrician.
  11. Hands should not be wet while handling electrical equipments. Electrical poles should not be used for hanging cloths etc.
  12. Rubber sole footwear has to be put on foot while handling electrical appliances.
  13. Every electrical appliance to be connected with a proper socket on the wall. For example, one 15A or 10A plug has to be inserted to the compatible socket only.
  14. Too many appliances are not to be connected to one socket outlet by any means to avoid overloading which may cause catching of fire.
  15. All connections should be periodically checked for tightness to avoid accidents.
  16. All single pole switches should always be placed in live wire only and not in the neutral wire.
  17. Correct size of fuse wires to be used. Use of oversize or undersize may give trouble unnecessarily.
  18. For replacing a blown fuse, main switch should first be switched off.

 Testing tools

Tester– It completes the circuit through our body, but we remain safe because the amount of current flowing through body is very less due to high resistance of the tester wire itself.

Megger– It is the instrument by which the insulation resistance of a conductor can be measured.

Conversion of AC to DC supply

For engineering and economic reasons, almost all supply systems in India are in AC system. But many electrical equipment and machines used in household and industrial purposes require DC supply for technical reasons, like DC motors are better for traction purposes such as tram cars,

electric locomotives etc. DC supply is also used in electrical arc welding for improved quality of welding. So, there is a need to convert AC supply to DC supply in hotel premises for particular machines. The process of converting AC to DC is known as rectification. This can be done by one of the following:-

  1. Generator set Rotary converter 3. Solid state rectifier 4. Mercury arc rectifier

Electric Tariff and energy bill

There are various systems of electric tariffs for charging consumers for electricity like one-part, two-part and three-part system. The word ’tariff’ means the schedule of rates framed by electric supply companies for their consumers. There are various factors to decide the tariff scheme. But mainly depend on type of consumers like domestic, commercial or industrial. BOT is the electrical commercial unit of energy and expressed in kWh, which is equal to 36,000 Joule.

1 BOT unit = 1 kWh = 1000 Wh = 36,000 Watt-second = 36,000 Joule

Calculation of electrical expenses based on wattage of loads and their running hours only from the following example:-

Problem: – Find out the bill for the month of September 2012 for the following loads in a domestic apartment.

  1. 06 nos. 100 watt bulbs working for 10 hours a day
  2. 05 nos. 60 watt ceiling fans working for 15 hours a day
  3. 01 no. 2 kW heater working for 5 hours a day
  4. 01 no. 3 kW oven working for 10 hours a day
  5. 01 no. 2 hp motor working for water pump running for 2 hours a day

There are two nos. electrical energy meters (one for motor and one for other loads) in the apartment. Electricity charges for 1 kWh (1 BOT unit) energy used is Rs.5.00 Meter rent for the month is Rs. 20.00 per meter.

Solution: – The month September has 30 days (be particular about this in case of leap year). Convert 2 hp motor to its kW equivalent. 1 hp = 746 Watt = 0.746 kW. So, 2 hp = 2 x 0.746 kW = 1.492 kW.

Now, find the energy consumed by each type of load in kWh = (power in watt x number of units for the particular type of load x hours run in a day x number of days of the month) / 1000.

If power is given in kW, division by 1000 is not needed.

Following this, we get as follows: –

  1. Energy consumed by 100 watt lamps = (100 x 6 x 10 x 30) / 1000 = 180 kWh
  2. Energy consumed by 60 watt fans = (60 x 5 x 15 x 30) / 1000 = 135 kWh
  3. Energy consumed by 2 kW heater = (2 x 1 x 5 x 30)  =  300 kWh
  4. Energy consumed by 3 kW oven = (3 x 1 x 10 x 30)  =  900 kWh
  5. Energy consumed by 2 hp (1.492 kW) motor = (1.492 x 1 x 2 x 30) = 89.52 kWh

                Total energy consumed by all loads during the month = 1604.52 kWh

  So, total electrical units consumed are 1605 BOT units (rounded off). Rate per unit = Rs. 5.00

 Amount of electricity charge = 1605 x 5 = Rs. 8025

Meter rent for 2 meters = Rs. 20 x 2 = Rs. 40.00

Therefore, total amount of bill = electricity charge + meter rent for the month

                                                  = Rs. 8025 + Rs. 40 = Rs. 8065

Earthing: The risk of shock can arise from damage to insulation, the presence of water, or a loose connection. Electricity always takes the path of least resistance to the earth. Protection against shock can therefore be given by ensuring that every circuit has an energy path to earth (known as earth-continuity circuit), which will conduct away harmlessly any leaking electricity.

There are two types of earthing, like metal conduit and metal-sheathed. When earthing is there the circuit protects the whole wiring and fixed appliances together with portable appliances if a three-pin plug is used.

Electric Lighting

One of the primary uses of electric energy is for artificial lighting. In most buildings lighting represents the second highest energy use, following electric motor requirements. Light, its reflection, and object visibility all are interrelated. A light source radiates energy that we cannot see. Air does not absorb or reflect that energy passing through it. As light energy strikes a surface, it may be absorbed and converted to heat, which lowers lighting efficiency. The surface may transmit some of the energy or light may be reflected. Then only we can see the reflected light.

Proper design of lighting is one of the key factors for successful functioning of the hotel industry.

The objectives of proper lighting are:-

  1. To provide good working conditions to prevent strain and fatigue to the personnel.
  2. To create proper ambience.
  3. To help people know the directions etc. by use of proper lighting signs.
  4. To maintain safety standards.
  5. To enhance security.
  6. To attract people.

Lamp is a source of light. A lamp is inserted into a lighting fixture. The combined lamp and lighting fixture is called a luminaire. Lamplight output is given in lumens. A lumen is a quantity of light. The lumen is the amount of light energy that strikes an area at a specific distance from a standard candle. If 1 lumen falls on a 1 square foot area of distance of 1 foot from a standard candle, it is called 1 foot-candle of light intensity, or if 1 lumen strikes 1 square metre of surface of a distance of 1 metre from a standard candle, it is called 1 lux.  Foot-candles or lux refer to the intensity of light.

Lighting design depends on the foot candle (lux) intensity required at the work surface. Proper intensity of light can increase the productivity of working personnel. The level of natural light on a bright sunny day is about 50,000 lux, on a cloudy day it is only 5,000 lux and moonlight produces only 0.2 lux.

Types of Lighting

Different types of common light sources such as common electric bulbs, fluorescent tube lights, mercury vapour lights, neon signs, sodium vapour lamps etc. are all familiar terms. All these light sources can be broadly classified into two basic types depending on the physical principles like- i) Resistance-type Lamp and ii) Electric Discharge Lamp. For example, incandescent lamps or general lighting service (GLS) lamps, tungsten-halogen (TH) lamps are resistance-type lamps, whereas fluorescent lamp, metal halide lamp, sodium vapour lamp, mercury vapour lamp etc. are electric-discharge type lamps.

Another type of lighting is Light-emitting Diode (LED) which is an electronic light source based on the semiconductor diode. When the diode is switched on, electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the colour of the light is determined by the energy gap of the semiconductor. The LED is usually small in area with integrated optical components to shape its radiation pattern and assist in reflection. These are powered by low-voltage DC supply. These are very efficient, durable, low cost, reliable with dimming feature, environment friendly etc. Many hotels are fast replacing fluorescent and incandescent lamps with these bulbs. They may even replace CFLs in near future as they produce more light per watt.

Lighting System

Depending on effects of lighting, several lighting systems are available. They are direct, semi direct, diffuse, semi indirect and indirect.

The most efficient lighting system is Direct lighting system. Here all the light is directed to the activity area. This is found in institutional buildings due to low installation and operating costs. Approximately 90% light goes downwards and 10% of light goes upward.

Semi direct lighting system diverts a portion of the light towards the ceiling (usually less than 40%) and a larger percentage is directed towards into the activity area. Most of the board, conference, and meeting rooms use this type of lighting. Though it is not as efficient as direct lighting system but most of the food service managers prefer it over direct lighting system.

Diffuse lighting system directs approximately equal amounts of light downward into the activity area and upward to the ceiling. It is mostly used in public areas, dinning rooms and conference rooms. Cost of installation and operating is almost double than direct or semi direct lighting.

Semi indirect lighting system directs between 10% to 40% of the light output directly to the activity area. These are costly to install and operate for high foot-candle (lux) intensities.

Indirect lighting system reflects 90% or more of the emitted light from the luminaire to the ceiling and upper walls of the room, and redirected from these surfaces down towards the activity area.

Generally, only direct, semi direct and diffuse lighting are recommended for large areas and rooms. The indirect and semi indirect systems are recommended only for small rooms where special effects are to be created, or where we want a relaxed environment such as cocktail lounge or in guest house.     

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